http://bugs.winehq.org/show_bug.cgi?id=11970
--- Comment #47 from Roderick Colenbrander thunderbird2k@gmx.net 2008-03-31 07:18:11 --- We have had the opengl pixel format limitation in wine for years. I did some basic testing on windows and it appears that on windows (depending on I guess the driver) you can indeed receive a depth + stencil format for this 'bad' request. It appears that ChoosePixelFormat returns the first format which matches the set requirements. Because the first format which matches the requirements has depth + stencil (this can heavily depend on the driver though) a driver can return that.
So you could say that it is a bug in the game as it should really ask for what it needs. Likely they didn't notice it because (most?) windows drivers return what they need anyway.
I'm not sure what to do about this. Perhaps we should sort the format list in some way but I wasn't able to discover a pattern in it.